A microsystem integrally including a microsize sensor or actuator fabricated using micromachining techniques based on semiconductor processes and a drive circuit (including a control circuit) therefor is known and described as “MEMS” (Micro Electro Mechanical System). FIG. 12 is a sectional side view of a conventional sensor system formed as a MEMS. This sensor system 150 includes a ceramic substrate 70, a sensor device 74, an integrated circuit 75, a mounting external electrode 77, and a sealing material 78. The ceramic substrate 70 has a wiring pattern 76.
The sensor device 74 is designed to serve as an angular velocity sensor which includes a sensor body 71 made of a silicon-based material, an upper sealing member 72 made of glass, and a lower sealing member 73 made of glass. The upper and lower sealing members 72, 73 are provided as a means to house the sensor body 71 in an airtight manner. The integrated circuit 75 is designed to serve as a drive circuit for driving (and controlling) the sensor device 74, and formed as a bare chip connected through a bump to the wiring pattern 76 formed on the ceramic substrate 70. That is, the integrated circuit 75 is flip-chip-mounted on the ceramic substrate 70. The sensor device 74 is also mounted on the ceramic substrate 70 in the same manner as the flip-chip mounting. The sensor device 74 and the integrated circuit 75 are sealed by the resin sealing material 78. The sensor system 150 can be mounted on an external circuit board or the like through the mounting external electrode 77 connected to the wiring pattern 76. In this way, the sensor system 150 can be handled almost like a single integrated circuit.
As to the sensor device 74, a technique for sealing the silicon-based sensor body 71 with the glass upper and lower sealing members 72, 73 is commonly used in this field as disclosed, for example, in Japanese Patent Laid-Open Publication No. 2001-153881. However; this technique involves a problem about distortion or strain in the sensor body 71 to be caused by temperature changes due to the large difference in thermal expansion coefficient between silicon and glass. For example, this strain leads to change in resonance frequency of the sensor body 71 to cause temperature drift in characteristics as a sensor. Moreover, the sensor system 150 has a limitation in downsizing because the sensor device 74 and the integrated circuit 75 are mounted in such a manner that they are horizontally aligned with one another.